Founder of Les Fils Entrelacés
At first glance, superwash wool seems like a miracle fiber: machine washable, dryer safe, and no felting. Easy, convenient, and 100% wool. Or is it?
As you explore yarn, you will see labels that say “untreated wool” and “superwash.” So what’s the difference?
Superwash wool is wool that has undergone one of two treatments:
On the other hand, untreated wool is wool that has not undergone any treatment to reduce the risk of felting. This means that if a wool naturally has more risk of felting (fine, open scaled fibers like merino for example), then it is very important to be gentle while washing the garment.
To understand how felting works, we can think of wool fibers like velcro. Each fiber has scales, which can be more or less open depending on the breed of sheep.
More open = more risk of felting
More closed = less risk of felting
Another factor that influences felting is the strength of the fiber. Finer fibers are more likely to break, become tangled, and felt.
When we dissolve the scales, we smooth out the fiber (which reduces the risk of felting) but we also make it weaker. This means that to compensate, a polymer is used to fill the gaps and strengthen the fiber.
The second method, coating without the chlorine treatment, creates a plastic barrier that pins down the scales so they cannot hook onto other fibers and felt.
Yes!
Untreated wool has many natural properties, but two are most affected by the superwash treatment:
These two properties exist thanks to…the cortex & the matrix!
However, when we coat wool fibers with a polymer, we seal the surface and block air and humidity from moving in and out. The fiber can no longer help regulate temperature; humidity stays on the surface instead of circulating through the fiber, just as with other synthetics. In turn, this trapped surface moisture can become a breeding ground for bacteria.
The cortex (para & ortho-cortical cells) and the matrix in combination with your body heat work together like this:
What does that mean for temperature regulation and anti-microbial/fungal properties?
IN THE HEAT
More sweating → more moisture in the matrix → wind blows, moisture evaporates → evaporative cooling.
**If we spin the fiber to trap a lot of air (woolen spun) and then knit it densely, we will feel hotter. For hot-weather wear, we want a spinning method that squeezes out air (worsted spun) and a fabric that is woven or openly knit.
IN THE RAIN
Rain water absorbed by the matrix + Pockets of air in the cortex warmed by our body heat → Water is warmed by the air pockets and this is why we feel warm even when wet!
**Here, spinning woolen (to trap lots of air) and knitting densely will help the cortex and matrix do their work. A dense knit uses more wool and creates more surface area to hold heat.
IN THE COLD
Warm air in the cortex pockets + dry winter air and less sweating (less moisture in the matrix) → no evaporative cooling, only warm air retained → you feel warm.
**Again, woolen spinning and dense knitting help trap hot air and keep it from escaping.
The rise of the electric washing machine had a lot to do with it!
By the 1940s, 60% of all wired households in the USA had an electric washing machine. Adoption of the electric washing machine varied from place to place (with the UK only reaching a 60% adoption rate by the 1970s) but everywhere it spread, it reflected a desire to spend less time on household labor and more time in paid work or leisure.
Washing a family’s clothes by hand could take a full day or more, so the machine was an obvious time-saver. But wool garments did not fare well in the new machines: agitation caused felting and severe shrinkage.
At the same time, synthetic fibers that do not felt under agitation became widespread. With both machine convenience and synthetics available, many consumers moved away from wool, towards fibers like nylon and acrylic.
To compete with synthetics and offer easy-care wool, the industry developed superwash wool.
Although we can all agree that superwash wool is extremely convenient and reduces the stress surrounding the risk of felting, we can also agree that this process denatures the wool, and could be harmful to the environment.
With superwash, microplastics shed from the fibers after every wash and wear, and the chemicals used to achieve this felting-free wool are toxic to water sources if not disposed of properly.
But what is the solution?
In my opinion, the solution is twofold:
1) Keeping perspective: We need to remember that, unlike the people of the 19th and early 20th centuries, almost all of us own washing machines that we use to wash the vast majority of our clothing extremely quickly. This means that the time we spend hand washing our few woolen garments still pales in comparison to the hours and sometimes days spent doing laundry entirely by hand.
**Additionally, untreated wool garments do not need to be washed as often as other garments due to their natural properties!
To wash untreated wool, all you need to really do is :
Realistically, that’s 3-5 minutes of active washing; the rest is time you can spend doing other things!
2) Choosing types of wool that do not felt as easily: For garments that need to be washed more often (like socks), hand washing can seem daunting (although the process is the same as listed above and you could wash a bunch of pairs at once!). In these cases, it’s important to pick a type of wool that is less likely to break and felt and usually this means that the wool is either coarser or has very flat scales (like mohair).
**Types of wool that are less likely to felt:
Making a choice about superwash wool is an extremely personal one and is often decided on a case-by-case basis. I believe in making enlightened decisions, and that starts with bringing transparency to an area of expertise that is often very “top secret” and slathered in a thick coat of marketing.
If the natural properties of wool are something that you want to take advantage of, it’s important to understand that unfortunately, you will not be able to do so with superwash. On the flipside, if washing all your garments in the washing machine is extremely important to you, you will not necessarily be able to get that out of all untreated wool.
As with most things, there isn’t one right answer and not one thing that is necessarily “better” than another. There are always options that are more fitting for your needs, and I hope this article was able to shed some light on the topic to help you decide!
The structure of wool fibers. https://shop.britishwool.org.uk/the-structure-of-wool/
Bowden, S., & Offer, A. (1994). Household Appliances and the Use of Time: The United States and Britain Since the 1920s. The Economic History Review, 47(4), 725–748. https://doi.org/10.2307/2597714
Pantzar, M. (2003). Tools or Toys: Inventing the Need for Domestic Appliances in Postwar and Postmodern Finland. Journal of Advertising, 32(1), 83–93. http://www.jstor.org/stable/4622152
Robson, D., & Ekarius, C. (2011). The Fleece & Fiber Sourcebook: More than 200 fibers from animal to spun yarn. Storey Publications.
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